Research will be continued on the immunosuppression of idiotypic antibodies in inbred mice. The idiotypic antibody used is anti-p-azophenylarsonate (anti-Ar) antibody of strain A/J mice. We plan to work out methods for suppressing the cross-reactive idiotype in vitro. This will be done by treating cells with antiidiotypic antibody prior to adoptive transfer. Parameters to be investigated include the time and te,perature of exposure to antiidiotypic antibody and the effect of complement. Other variables will eventually be explored. The purpose is to elucidate the reactions which result in idiotypic suppression. A second major project is based on the finding of others that, in an adoptive transfer system, the presence of allotypically suppressed spleen cells prevents the expression of that allotype by normal cells which would otherwise express it in irradiated recipient mice. We will carry out analogous experiments with idiotypically suppressed cells to determine whether a similar mechanism is operative. The results should bear on the question as to whether prolonged suppression of idiotype is caused by the presence of suppressor T cells.